PfsModellShifts

Remarks:

The ModellShifts collection allows the access to the shifts of a
time model. The single shifts consist of a number and a period of
time (from/to), when the shift is active. Any number of breaks can
be defined for each shift. The breaks interrupt the production and
are inactive states. The period of time of a shift has to be
unique, i.e. it is not possible to define a shift within a
shift.